This invention relates to engineering intrinsic properties of particles, of articles manufactured by consolidation of particles, and of coatings formed from particles, and more particularly concerns the manufacture of articles and coatings engineered to have preselected thermal conductivities and coefficients of thermal expansion that match those of materials to which the articles and coatings are attached.
According to the Lacce "Rule of Mixtures," the intrinsic physical properties (e.g., thermal conductivity, coefficient of thermal expansion) of a heterogeneous article composed of at least two thoroughly mixed materials tend to vary approximately linearly with respect to the ratio of the volume of one of the materials to the volume of another of the materials. For example, a heterogeneous article composed of a 50-50 volumetric mixture of one material that has a low coefficient of thermal expansion and another material that has a high coefficient of thermal expansion can be expected to have a coefficient of thermal expansion that is the average of the coefficients of thermal expansion of the two materials.
In a known method of manufacturing heterogeneous articles, a mixture of two metal powders which have different thermal conductivities and coefficients of thermal expansion, is compacted and sintered to produce the article. The article has an engineered coefficient of thermal expansion that approximately matches the coefficient of thermal expansion of an object to which the article is designed to be attached, and an engineered thermal conductivity.